Lemon Demon's eerie music already suggests such a specific kind of relationship dynamic, doesn't it? Most stories I've stumbled across play on the idea of the 'Senpai' figure being the only one who can perceive or interact with the entity within the weird, glitched-out digital soundscape of the music. A recurring theme is the demon acting as a manifestation of the Senpai's own repressed anxieties or desires—like, this popular student externally admired but internally a wreck, and the demon both torments and comforts them in this grotesque, possessive way. It's a great vehicle for exploring psychological horror within a school setting.
There's also a surprising amount of body horror and transformation stuff, like the Senpai slowly becoming something non-human because of the prolonged contact. The power imbalance is inherently baked in; the demon has all this chaotic, reality-warping energy, and the Senpai is trying to maintain control and normality. I guess that's the core: an unstable, co-dependent relationship built on fascination and fear, not really romance in a traditional sense. It gets pretty dark, which fits the source material's vibe perfectly.